Ethylene copolymers with alpha,beta-unsaturated carboxylic acids are known to be very good hot melt adhesives suitable for bonding plastic to metal or to another plastic layer. However, when an -antimony oxide/organo-halogen system is incorporated into the ethylene/alpha,beta-unsaturated carboxylic acid copolymer, and the resulting fire-retarded copolymer is exposed to high temperatures, such, for example, as are encountered during extrusion (typically in the range from 200 to 280 deg. C.), the copolymer reacts with the antimony oxide as evidenced by a decrease of the polymer's melt index. Further reduction of melt index occurs on storage. Such lowering of the melt index is undesirable because it leads to more difficult and less uniform processing.
There is, therefore, a great need for a thermally stable fire-retardant ethylene/alpha,beta-unsaturated carboxylic acid copolymer composition.